Combination of Propulsion Engine with Air Lubrication System for Ultimate Ship Efficiency

Abstract

Gradually toughening requirements on reducing ships energy consumption and gas emissions raise the importance of adoption of various energy saving systems on engine and ship. However, a correct coupling of the various systems is of great importance in achieving the ultimate ship efficiency. One of the examples of such a coupling is the application of air lubrication for the ship hull resistance reduction, air for which is bled from the scavenging system of the main engine. This system has found an application on a real ship, the range of operation is limited though. This paper proposes the way of extending operation of air lubrication system by taking advantage of power take-in capabilities of recently developed assist systems for turbochargers. As was found experimentally and confirmed analytically the increase of air bleeding rate requires a proportional increase of compressor’s assist power and droop control of scavenging pressure can reduce assist power demand considerably.